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TECHNICAL PAPERS: Fluids/Heat/Transport

Numerical Simulation of Local Blood Flow in the Carotid and Cerebral Arteries Under Altered Gravity

[+] Author and Article Information
Changsung Sean Kim, Dochan Kwak

 NASA Ames Research Center, M∕S T27B-1, Moffett Field, CA 94035-1000

Cetin Kiris1

 NASA Ames Research Center, M∕S T27B-1, Moffett Field, CA 94035-1000ckiris@mail.arc.nasa.gov

Tim David

Department of Mechanical Engineering,  University of Canterbury, Private Bag 4800, Christchurch 8020, New Zealand

1

Corresponding author.

J Biomech Eng 128(2), 194-202 (Sep 25, 2005) (9 pages) doi:10.1115/1.2165691 History: Received January 23, 2004; Revised September 25, 2005

A computational fluid dynamics (CFD) approach was presented to model the blood flows in the carotid bifurcation and the brain arteries under altered gravity. Physical models required for CFD simulation were introduced including a model for arterial wall motion due to fluid-wall interactions, a shear thinning fluid model of blood, a vascular bed model for outflow boundary conditions, and a model for autoregulation mechanism. The three-dimensional unsteady incompressible Navier-Stokes equations coupled with these models were solved iteratively using the pseudocompressibility method and dual time stepping. Gravity source terms were added to the Navier-Stokes equations to take the effect of gravity into account. For the treatment of complex geometry, a chimera overset grid technique was adopted to obtain connectivity between arterial branches. For code validation, computed results were compared with experimental data for both steady-state and time-dependent flows. This computational approach was then applied to blood flows through a realistic carotid bifurcation and two Circle of Willis models, one using an idealized geometry and the other using an anatomical data set. A three-dimensional Circle of Willis configuration was reconstructed from subject-specific magnetic resonance images using an image segmentation method. Through the numerical simulation of blood flow in two model problems, namely, the carotid bifurcation and the brain arteries, it was observed that the altered gravity has considerable effects on arterial contraction∕dilatation and consequent changes in flow conditions.

Copyright © 2006 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Analogy of arterial network to electric circuit

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Figure 2

Schematic definition of a carotid arterial bifurcation (21)

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Figure 3

Axial velocity profiles on the symmetry (upper) and its perpendicular plane (lower) in the ICA at Re=270(21)

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Figure 4

Inflow waveform regenerated using 12 harmonics (22)

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Figure 5

Comparison of axial velocity profiles between computation and experiment at three different phases (22)

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Figure 6

Streaklines through a carotid arterial bifurcation at three different points in a cycle. (a) Systolic acceleration phase (t∕T=0.28); (b) systolic deceleration phase (t∕T=0.36); (c) minimum flow rate phase (t∕T=0.58).

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Figure 7

Temporal wall shear stress during the pulse cycle at three different points around the ICA sinus (ICA: internal carotid artery, ECA: external carotid artery)

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Figure 8

Gravitational effects on wall motion and axial velocity profiles at systolic deceleration phase

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Figure 9

Gravitational effect on wall shear stress distribution during the systolic deceleration phase. (Percent change of diameter with respect to microgravity case.)

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Figure 10

Chimera overset grid with ten domains for an idealized Circle of Willis configuration

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Figure 11

Collateral circulation with the left internal carotid artery 20% stenosed under autoregulation. (Magnitude of normalized velocity in color contour.)

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Figure 12

Percent changes of flow rate in left middle and anterior cerebral arteries under autoregulation (ACA: anterior cerebral artery; MCA: middle cerebral artery; ICA: internal carotid artery)

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Figure 13

Image segmentation from a magnetic resonance image for a subject-specific Circle of Willis. (MRA provided by John Fink and Mike Hurrell at Christchurch Hospital, New Zealand.)

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Figure 14

Three-dimensional reconstruction of an anatomical Circle of Willis configuration

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Figure 15

Time-averaged blood flow within compliant walls under microgravity (0G). (Magnitude of normalized velocity in color contour.)

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Figure 16

Time-averaged blood flow within compliant walls in standing posture (1G). (Percent change of diameter with respect to microgravity case.)

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Figure 17

Time-averaged blood flow within compliant walls in hand-standing posture (−1G). (Percent change of diameter with respect to microgravity case.)

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Figure 18

Time-averaged wall shear stress distribution under microgravity (0G)

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Figure 19

Time-averaged wall shear stress distribution in standing posture (1G)

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